The overall aim of this project is to identify cell specific molecular markers in neurons of Ascaris, especially the small molecules that are involved in intercellular signalling. In the past we have concentrated on the classical chemical transmitters involved in synaptic transmission. We are now most interested in the role of neuropeptides both in synaptic transmission and in non- synaptic intercellular signalling. In the present grant period we will concentrate on obtaining the sequences of endogenous bioactive Ascaris peptides, so that they can be synthesized in large enough quantities to permit electrophysiological experiments on their action on the neuromuscular system of Ascaris. Gaining a basic understanding of the Ascaris nervous system is important since Ascaris is a model nematode in which to investigate the control of locomotion in nematodes. The Ascaris motor nervous system is anatomically similar to that of other nematodes, so it is reasonable to assume that this similarity will also apply at the functional level. By studying the mechanisms underlying the activity of the neuromuscular system of Ascaris. and the role of neuropeptides in controlling this activity, general principles applying to other nematodes will be found. This basic understanding of the nematode nervous system will make a contribution to parasite biology, and allow differences in the biology between host and parasite to be identified as targets for anthelmintic drugs. In view of the agricultural impact o? nematodes on food supplies, and the problems they cause as animal and human parasites, especially in tropic and economically less- developed countries, this is an important health-related goal.